Five heavily armed assailants wearing masks made off with $85,291 from the casino at the Hotel Gran Melia in the northern coastal town of Rio Grande, Puerto Rican police said Friday.

None of the roughly 40 patrons and employees inside the casino at the time of Thursday night's robbery was hurt.

The investigation and search for the perpetrators is under way, but authorities have no leads yet, Puerto Rico police chief Emilio Diaz Colon told Efe.

The robbery followed the same modus operandi as a heist in March at the same casino, Efe learned from police Maj. Emilio Ramos.

While media outlets said the vehicle used by the robbers was found in the wee hours of Friday, police did not confirm the story.

Puerto Rico is in the midst of a crime wave marked by a dozen murders a week on average and numerous armed robberies.

Authorities attribute most of the mayhem to turf battles over control of the illegal drug trade in public housing complexes, yet the violence has also spread into upscale neighborhoods favored by tourists.